A novel method for modeling the air gap flux density of the axial-flux permanent magnet eddy current coupler considering the end-effect

In this study, an analytical model is established to efficiently compute the magnetic field and unbalanced magnetic pull (UMP) in axial-flux permanent-magnet motors (AFPMMs). The effects of stator slotting, end effect, and rotor eccentricity on the magnetic field and forces were investigated. Static and dynamic eccentricities are analyzed and considered in the model. An effective function of the air gap permeance was introduced for effect of the stator slots to compute the flux density. A specific coefficient function is defined to calculate the end effect. A Fourier transform is used to compute the variations of the permanent-magnet remanence and the air gap permeance due to the slotted stator opposite to a slotless stator. The unbalanced magnetic forces were evaluated as a function of the air gap magnetic field using analytical equations. The proposed analytical method dramatically reduces the model size and computational time. It can be applied to the analysis of AFPMMs and is much faster than the three-dimensional finite element method (FEM). By comparing with the obtained using the FEM, the model results are validated.

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A Novel Axial-Flux Dual-Stator Toothless Permanent Magnet Machine for Flywheel Energy Storage

Symmetry ◽

10.3390/sym14010061 ◽

2022 ◽

Vol 14 (1) ◽

pp. 61

Author(s):

Yong Zhao ◽

Fangzhou Lu ◽

Changxin Fan ◽

Jufeng Yang

Keyword(s):

Energy Storage ◽

Permanent Magnet ◽

Flux Density ◽

Load Capacity ◽

Core Loss ◽

Torque Ripple ◽

Air Gap ◽

Flywheel Energy Storage ◽

Axial Flux ◽

Permanent Magnet Machine

This paper presents an alternative system called the axial-flux dual-stator toothless permanent magnet machine (AFDSTPMM) system for flywheel energy storage. This system lowers self-dissipation by producing less core loss than existing structures; a permanent magnet (PM) array is put forward to enhance the air–gap flux density of the symmetrical air gap on both sides. Moreover, its vertical stability is strengthened through the adoption of an axial-flux machine, so expensive active magnetic bearings can be replaced. The symmetry configuration of the AFDSTPMM system is shown in this paper. Then, several parts of the AFDSTPMM system are optimized thoroughly, including stator windings, number of pole pairs and the PM parameters. Further, the performance of the proposed PM array, including back-EMFs, air–gap flux density, average torque, torque ripple and over-load capacity, are compared with the Halbach PM array and spoke PM array, showing the superiority of proposed configuration. Finally, 3D simulations were made to testify for the 2D analyses.

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An analytical approach and finite element evaluation of leakage fluxes of the PMs in a non-slotted axial flux permanent magnet machine

COMPEL The International Journal for Computation and Mathematics in Electrical and Electronic Engineering ◽

10.1108/compel-05-2017-0196 ◽

2018 ◽

Vol 37 (3) ◽

pp. 1085-1098

Author(s):

Reza Mirzahosseini ◽

Ahmad Darabi ◽

Mohsen Assili

Keyword(s):

Finite Element ◽

Permanent Magnet ◽

Flux Density ◽

Accurate Determination ◽

Three Dimensional ◽

Air Gap ◽

Design Stage ◽

Axial Flux ◽

Content Type ◽

Leakage Flux

Purpose Consideration of leakage fluxes in the preliminary design stage of a machine is important for accurate determination of machine dimensions and prediction of performance characteristics. This paper aims to obtain some equations for calculating the average air gap flux density, the flux density within the magnet and the air gap leakage flux factor. Design/methodology/approach A detailed magnetic equivalent circuit (MEC) is presented for a TORUS-type non-slotted axial flux permanent magnet (TORUS-NS AFPM) machine. In this MEC, the leakage flux occurring between two adjacent magnets and the leakage fluxes taking place between the magnet and rotor iron at the interpolar, inner and outer edges of the magnets are considered. According to the proposed MEC and by using flux division law, some equations are extracted. A three-dimensional finite element method (FEM) is used to evaluate the proposed analytical equations. The study machine is a 3.7 kW and 1,400 rpm TORUS-NS AFPM machine. Findings The air gap leakage flux factor, the average air gap flux density and the flux density within the magnet are calculated using the proposed equations and FEM. All the results of FEM confirm the excellent accuracy of the proposed analytical method. Originality/value The new equations presented in this paper can be applied for leakage flux evaluating purposes.

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Optimization of Air Gap for Axial Flux Machine

10.46532/978-81-950008-1-4_077 ◽

2020 ◽

pp. 351-353

Author(s):

Vignesh C J ◽

Vivekanandan S ◽

Kamalkumar V ◽

Balamurugan K

Keyword(s):

Flux Density ◽

Eddy Current ◽

Air Gap ◽

Axial Flux ◽

Eddy Current Losses ◽

Electromagnetic Design ◽

Air Gaps ◽

Copper Loss ◽

The Cost ◽

Rotor Structure

The analyses the axial flux permanent magnet generator (AFPMG) dual stator single rotor structure. For the valuation of analytical results, the electromagnetic design of AFPMG is done and compared with various air gaps to flux density and power density. In the axial flux design air gap to flux density is improvement for different air gap are analyzed. This machine is gauge with certain criteria such as the cost, the copper loss, the eddy current losses and the flux density.

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A novel analytical calculation of magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping

International Journal of Applied Electromagnetics and Mechanics ◽

10.3233/jae-201505 ◽

2020 ◽

pp. 1-15

Author(s):

Jianqi Li ◽

Yu Zhou ◽

Jianying Li

Keyword(s):

Magnetic Field ◽

Conformal Mapping ◽

Permanent Magnet ◽

Flux Density ◽

Analytical Method ◽

Electromotive Force ◽

Analytical Calculation ◽

Air Gap ◽

Permanent Magnet Machines ◽

Peak Value

This paper presented a novel analytical method for calculating magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping. Firstly, flux density without slots and complex relative air-gap permeance of slotted air gap are derived from conformal transformation separately. Secondly, they are combined in order to obtain normalized flux density taking account into the slots effect. The finite element (FE) results confirmed the validity of the analytical method for predicting magnetic field and back electromotive force (BEMF) in the slotted air gap of spoke-type permanent-magnet machines. In comparison with FE result, the analytical solution yields higher peak value of cogging torque.

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Design of a New 1D Halbach Magnet Array with Good Sinusoidal Magnetic Field by Analyzing the Curved Surface

Sensors ◽

10.3390/s21072522 ◽

2021 ◽

Vol 21 (7) ◽

pp. 2522

Author(s):

Guangdou Liu ◽

Shiqin Hou ◽

Xingping Xu ◽

Wensheng Xiao

Keyword(s):

Magnetic Field ◽

Magnetic Flux ◽

Permanent Magnet ◽

Flux Density ◽

Permanent Magnets ◽

Air Gap ◽

Curved Surface ◽

Magnetic Flux Density ◽

Sinusoidal Magnetic Field ◽

The Magnetic Field

In the linear and planar motors, the 1D Halbach magnet array is extensively used. The sinusoidal property of the magnetic field deteriorates by analyzing the magnetic field at a small air gap. Therefore, a new 1D Halbach magnet array is proposed, in which the permanent magnet with a curved surface is applied. Based on the superposition of principle and Fourier series, the magnetic flux density distribution is derived. The optimized curved surface is obtained and fitted by a polynomial. The sinusoidal magnetic field is verified by comparing it with the magnetic flux density of the finite element model. Through the analysis of different dimensions of the permanent magnet array, the optimization result has good applicability. The force ripple can be significantly reduced by the new magnet array. The effect on the mass and air gap is investigated compared with a conventional magnet array with rectangular permanent magnets. In conclusion, the new magnet array design has the scalability to be extended to various sizes of motor and is especially suitable for small air gap applications.

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DESIGN OF A SINGLE-PHASE RADIAL FLUX PERMANENT MAGNET GENERATOR WITH VARIATION OF THE STATOR DIAMETER

Jurnal Teknologi ◽

10.11113/jt.v81.12889 ◽

2019 ◽

Vol 81 (4) ◽

Author(s):

Hari Prasetijo ◽

Winasis Winasis ◽

Priswanto Priswanto ◽

Dadan Hermawan

Keyword(s):

Magnetic Flux ◽

Permanent Magnet ◽

Flux Density ◽

Single Phase ◽

Air Gap ◽

Wire Diameter ◽

Terminal Phase ◽

Magnetic Flux Density ◽

Phase Voltage ◽

Radial Flux

This study aims to observe the influence of the changing stator dimension on the air gap magnetic flux density (Bg) in the design of a single-phase radial flux permanent magnet generator (RFPMG). The changes in stator dimension were carried out by using three different wire diameters as stator wire, namely, AWG 14 (d = 1.63 mm), AWG 15 (d = 1.45 mm) and AWG 16 (d = 1.29 mm). The dimension of the width of the stator teeth (Wts) was fixed such that a larger stator wire diameter will require a larger stator outside diameter (Dso). By fixing the dimensions of the rotor, permanent magnet, air gap (lg) and stator inner diameter, the magnitude of the magnetic flux density in the air gap (Bg) can be determined. This flux density was used to calculate the phase back electromotive force (Eph). The terminal phase voltage (V∅) was determined after calculating the stator wire impedance (Z) with a constant current of 3.63 A. The study method was conducted by determining the design parameters, calculating the design variables, designing the generator dimensions using AutoCad and determining the magnetic flux density using FEMM simulation. The results show that the magnetic flux density in the air gap and the phase back emf Eph slightly decrease with increasing stator dimension because of increasing reluctance. However, the voltage drop is more dominant when the stator coil wire diameter is smaller. Thus, a larger diameter of the stator wire would allow terminal phase voltage (V∅) to become slightly larger. With a stator wire diameter of 1.29, 1.45 and 1.63 mm, the impedance values of the stator wire (Z) were 9.52746, 9.23581 and 9.06421 Ω and the terminal phase voltages (V∅) were 220.73, 221.57 and 222.80 V, respectively. Increasing the power capacity (S) in the RFPMG design by increasing the diameter (d) of the stator wire will cause a significant increase in the percentage of the stator maximum current carrying capacity wire but the decrease in stator wire impedance is not significant. Thus, it will reduce the phase terminal voltage (V∅) from its nominal value.

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